If your Windows 2000 domain controller didn't have any DNS configured at the time of promotion, your RAS and VPN clients may receive 127.0.0.1 for the DNS Server address. They may be unable to resolve host names and they may receive:
System error 53 has occurred.
The network path was not found
1. Right-click My Network Places, and press Properties.
2. Right-click the LAN icon for the NIC, and press Properties.
3. In the Components checked are used by this connection box, double-click Internet Protocol (TCP/IP).
4. Change the Prefered DNS Server: from 127.0.0.1 to the address of the NIC.
5. Press OK.
On the client computers:
1. Have the client disconnect and reconnect.
2. Have your Windows NT 4.0 and Windows 2000 clients statically configure the DNS Server address(es) in the Phone Book.